A few new details about Billy Maximoff's role in Agatha: Darkhold Diaries have been revealed, including his LGBTQ+ status and how the Scarlet Witch's son somehow returns from the dead.

Source: https://comicbookmovie.com/tv/marvel/agatha-coven-of-chaos/agatha-darkhold-diaries---new-details-emerge-about-billy-maximoffs-return-in-upcoming-disney-series-a205445

Extreme horror, the times in which the Scarecrow was holding off Ghost Rider with human shields and the Darkhold Redeemers were holding the door back against chaos.

Source: https://comicbook.com/comics/news/steve-orlando-miguel-ohara-spider-man-2099-interview/

Together, Agatha: Darkhold Diaries will likely expand the book's MCU lore and reveal new information about the Scarlet Witch's prophecy, confirming or denying the possibility of Scarlet Witch's return along the way.

Source: https://screenrant.com/agatha-darkhold-diaries-answer-wandavision-mcu-prophecy/